Web conveying device

ABSTRACT

A web conveying device configured to convey a web and rewind the web into a roll includes: a moving roller arranged between a send-in port for the web and a rewinding roll which is the web rolled, the moving roller configured to be movable in an up-down direction to apply tension to the web or release the tension; and a controller configured to perform control of moving the moving roller to an upper limit position in the up-down direction in an operation of stopping conveyance of the web.

1. TECHNICAL FIELD

The present invention relates to a web conveying device configured to convey a web which is a belt-shaped medium.

2. RELATED ART

The web is used to print, for example, a large volume of standard forms such as slips in one process. In this case, the web after printing in a printing device is rewound on a rewinding roll of a rewinding device. The web is fed to the printing device from, for example, a paper feed roll of a paper feeding device.

The conveyance speed of the web discharged after printing from the printing device is constant once the web accelerates to certain speed. Meanwhile, the peripheral speed of the rewinding roll on which the web is rewound changes depending on the diameter of the rewinding roll.

The rewinding device is provided with a moving roller configured to be movable in the up-down direction by its own weight to absorb the aforementioned speed difference and prevent generation of slack in the web. A lower surface of the moving roller is supported by the web and the moving roller moves downward when the discharge speed on the printing device side is higher than the peripheral speed of the web rewound on the rewinding roll and moves upward in the opposite case.

The moving roller applies tension to the web between the printing device and the rewinding device, suppresses generation of slack, and allows the web to stably proceed without occurrence of wrinkles, crease, or paper jam. Since the moving roller is supported by the web, when the printing is stopped, the moving roller excessively pulls out the web from the paper feed roll by its own weight.

For example, Patent Literature 1 (Japanese Patent Application Publication No. 2015-120268) discloses an invention which lifts the moving roller to prevent slack when the conveyance speed of the web is reduced.

SUMMARY

However, the invention disclosed in Patent Literature 1 lowers the moving roller to set the web to the tensioned state when the printing is stopped. Lowering the moving roller when the printing is stopped causes the web to be excessively pulled out from the paper feed roll and increases the amount of wasted paper.

The present invention has been made in view of the aforementioned problem and an object is to prevent a web from being excessively pulled out from a paper feed roll and reduce waste of the web in a web conveying device.

Solution to Problem

In order to achieve the aforementioned object, the web conveying device according to one aspect of the present invention is a web conveying device configured to convey a web and rewind the web into a roll, the web conveying device including: a moving roller arranged between a send-in port for the web and a rewinding roll which is the web rolled, the moving roller configured to be movable in an up-down direction to apply tension to the web or release the tension; and a controller configured to perform control of moving the moving roller to an upper limit position in the up-down direction in an operation of stopping conveyance of the web.

The web conveying device according to the present invention can reduce waste of the web.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described with reference to the accompanying drawings wherein:

FIG. 1 is a flowchart illustrating an outline of processing steps of a comparative example in the case where conveyance of a web is stopped:

FIG. 2 is a diagram schematically illustrating a functional configuration example of a web conveying system according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating a more specific functional configuration example of a rewinding device illustrated in FIG. 2;

FIG. 4 is a flowchart illustrating processing steps of a controller illustrated in FIG. 2:

FIG. 5 is a diagram schematically illustrating a configuration example of a moving roller illustrated in FIG. 3 as viewed in a conveyance direction of continuous paper:

FIG. 6 is a flowchart illustrating processing steps of the controller in the case where the diameter of a rewinding roll illustrated in FIG. 2 is small;

FIG. 7 is a flowchart illustrating processing steps of the controller in the case where the diameter of the rewinding roll illustrated in FIG. 2 is at an intermediate level:

FIG. 8 is a flowchart illustrating processing steps of the controller in the case where the diameter of the rewinding roll is large:

FIG. 9 is a flowchart illustrating processing steps in error processing of the web conveying system illustrated in FIG. 2;

FIG. 10 is a flowchart illustrating schematic processing steps of stop processing in a conveyance-related error; and

FIG. 11 is a flowchart more specifically describing processing illustrated in FIG. 10.

DETAILED DESCRIPTION Comparative Example

Operations of a comparative example in the case where a print system stops conveyance of a web are described before an embodiment of the present invention is described.

The conveyance speed of the web in the print system is controlled such that a moving roller of a rewinding device is located substantially at the center of its moving range. The moving roller arranged between a web send-in port of the rewinding device and a rewinding roll is movable in an up-down direction by its own weight and a lower surface of the moving roller is supported by the web.

Accordingly, the moving roller acts a buffer device (buffer) which absorbs a speed difference between conveyance speed of the web discharged after printing from a printing device and peripheral speed of the web rewound on the rewinding roll. The moving roller is generally referred to as a dancer roller.

The peripheral speed (diameter) of the rewinding roll constantly changes. Meanwhile, the conveyance speed of the web on the printing device side is fixed.

Accordingly, when the conveyance speed of the web on the printing device side is higher than the peripheral speed of the rewinding roll, the moving roller moves downward in the moving range. Moreover, when the conveyance speed of the web on the printing device side is lower than the peripheral speed of the rewinding roll, the moving roller moves upward in the moving range.

Accordingly, during the conveyance of the web, the peripheral speed of the rewinding roll (number of revolutions of a shaft of the rewinding roll) is controlled such that the moving roller is located at the center of its moving range. Accordingly, the moving roller is located near the center of its moving range during the printing of the web.

When the printing is stopped, the printing device and the rewinding device are simultaneously stopped. However, since the rotating rewinding roll has a certain force of inertia, the rewinding roll needs to be stopped with predetermined stop time provided. Note that, this system is referred to as print system because this system includes the printing device and conveys the web after printing. However, when the printing device initially delivers paper to the rewinding roll, the printing device only performs the operation of conveying the web.

Accordingly, the printing device is described hereafter while being referred to as conveying device. Moreover, this system is referred to as web conveying system.

FIG. 1 is a flowchart illustrating an outline of processing steps in the case where the conveyance of the web is stopped.

The web conveying system determines whether a predetermined amount of web has been conveyed (step S1). When the conveyance amount of the web reaches the predetermined amount (YES in step S1), the web conveying system applies brake to the conveying device and the rewinding device simultaneously and starts deceleration (step S2).

The aforementioned control of arranging the moving roller near the center of the moving range is executed also during the deceleration (step S3). The aforementioned control is repeated (loop of NO in step S4) until the stop of the conveyance of the web is detected (YES in step S4).

After the stop of conveyance, the moving roller falls to the lower limit position of its moving range by its own weight. Accordingly, the web is excessively pulled out from a paper feed roll of a web feeding device. The web feeding device needs to be provided with a brake to prevent this pulling out. As a result, the configuration of the web conveying system becomes complex and the cost increases.

An object of a web conveying system according to an embodiment of the present invention is to reduce waste of the web excessively pulled out from the paper feed roll at the stop of printing in a simple configuration. The web conveying system can reduce the waste of the web without being provided with a brake on the web feeding device side.

An embodiment of the present invention is described below with reference to the drawings. Note that portions and components which are the same or equivalent among the drawings are denoted by the same or equivalent reference signs and description thereof is omitted or simplified.

(Web Conveying System)

FIG. 2 is a diagram schematically illustrating a functional configuration example of the web conveying system according to the embodiment of the present invention. A web conveying system 100 illustrated in FIG. 2 includes a web feeding device, a conveying device 20, and a rewinding device 30. The web feeding device is a paper feeding device 10 with a simple configuration having no brake. The printing method of the conveying device 20 is, for example, an inkjet method.

The web feeding device unwinds the rolled web and feeds the web to the conveying device 20. Moreover, the rewinding device 30 rewinds the web discharged from the conveying device 20 into a roll.

In FIG. 2, the left side is upstream in a printing step executed by the web conveying system 100 and the right side is downstream in the printing step. Directions orthogonal to the left-right direction in FIG. 2 are defined as up and down, a direction away from the viewer of FIG. 2 is defined as front (F), and a direction toward the viewer of FIG. 2 is defined as rear (R).

Hereafter, description is given by using continuous paper P as an example of the web. Accordingly, description is given by using the paper feeding device 10 as an example of the web feeding device.

The paper feeding device 10 includes a paper feed roll 11 and guide rollers denoted by no reference signs. The rolled web in the paper feed roll 11 is pulled out by motion of conveyance rollers (not illustrated) in the conveying device 20.

The rewinding device 30 illustrated in FIG. 2 includes a send-in port 31, paired guide rollers 32, 33, a moving roller 34, a moving roller holder 35, and a rewinding roll 36. The rewinding roll 36 is a roll in which the continuous paper P is wound on a paper pipe 36 a. FIG. 2 illustrates only a main conveyance route of the continuous paper P and illustration of the other configurations are omitted.

The paired guide rollers 32, 33 guide the continuous paper P conveyed from the send-in port 31 to the rewinding roll 36 rewound on the paper pipe 36 a. The moving roller 34 press down the continuous paper P between the guide roller 32 and the rewinding roll 36 in the direction of gravity by its own weight to apply tension to the continuous paper P. This tension reduces wrinkles formed in the continuous paper P and prevents occurrence of uneven winding in the rewinding roll 36.

The moving roller holder 35 releases the tension applied to the continuous paper P by using a holding stage 35 e which holds the moving roller 34 and prevents it from falling in an operation of stopping conveyance of the continuous paper P. Since the moving roller 34 is held at the upper limit position in the moving range thereof by the holding stage 35 e, the continuous paper P is not excessively pulled out from the paper feed roll 11.

The conveying device 20 includes a main shaft motor 21 (first motor) and a controller 22. The conveying device 20 and the rewinding device 30 are connected to each other by a communication cable (not illustrated) and are configured such that, for example, signals of a conveyance stop instruction for stopping the conveyance and similar instructions generated by the conveying device 20 are shared by the conveying device 20 and the rewinding device 30.

Note that configurations which form the conveying device 20 and which are not directly related to the present invention such as an inkjet head are all omitted. Moreover, the controller 22 may be included in the rewinding device 30.

The main shaft motor 21 conveys the continuous paper P. The main shaft motor 21 rotates the conveyance rollers (not illustrated) connected thereto via a speed reducer (not illustrated) and conveys the continuous paper P nipped by the conveyance rollers.

The controller 22 moves the moving roller 34 to the upper limit position in the up-down direction in the operation of stopping conveyance of the continuous paper P. When the moving roller 34 is at the upper limit position in its moving range, the length of the continuous paper P between the guide roller 32 and the rewinding roll 36 is at the minimum.

As described above, the web conveying system 100 according to the embodiment is the web conveying system including the conveying device 20 configured to convey the continuous paper P and the rewinding device 30 configured to rewind the continuous paper P into a roll and, in the web conveying system, the rewinding device 30 includes: the moving roller 34 arranged between the send-in port 31 for the continuous paper P and the rewinding roll 36 which is the continuous paper P rolled, the moving roller 34 configured to be movable in the up-down direction to apply tension to the continuous paper P; and the moving roller holder 35 configured to release the tension by using the holding stage 35 e configured to hold the moving roller 34 and prevent it from falling in the operation of stopping conveyance of the continuous paper P, and the conveying device 20 or the rewinding device 30 includes the controller 22 configured to move the moving roller 34 to the upper limit position in the up-down direction in the operation of stopping conveyance of the continuous paper P.

Note that the moving roller holder 35 may be omitted. Specifically, the moving roller 34 may not be held from below by the holding stage 35 e. A mechanism configured to pull up the moving roller 34 and prevent it from falling may be used. A specific configuration in this case is described later.

Specifically, the web conveying system 100 according to the embodiment is the web conveying system including the conveying device 20 configured to convey the continuous paper P and the rewinding device 30 configured to rewind the continuous paper P into a roll and, in the web conveying system, the rewinding device 30 includes the moving roller 34 arranged between the send-in port 31 for the continuous paper P and the rewinding roll 36 which is the continuous paper P rolled, the moving roller 34 configured to be movable in the up-down direction to apply tension to the continuous paper P or release the tension, and the conveying device 20 or the rewinding device 30 includes the controller 22 configured to move the moving roller 34 to the upper limit position in the up-down direction in the operation of stopping conveyance of the continuous paper P.

Moreover, the conveying device 20 and the rewinding device 30 may be integrated. Specifically, in the embodiment, the conveying device 20 and the rewinding device 30 may be configured as a web conveying device which performs printing on the continuous paper P supplied from the paper feeding device 10 and which rewinds the continuous paper P after printing on the rewinding roll 36. The web conveying device 23 (not illustrated) in this case is a web conveying device configured to convey the continuous paper P and rewind the continuous paper P into a roll and includes: the moving roller 34 arranged between a send-in port for the continuous paper P and the rewinding roll 36 which is the continuous paper P rolled, the moving roller 34 configured to be movable in the up-down direction to apply tension to the continuous paper P or release the tension; and the controller 22 configured to perform control of moving the moving roller 34 to the upper limit position in the up-down direction in the operation of stopping conveyance of the continuous paper P. In this configuration, the tension applied to the continuous paper P by the weight of the moving roller 34 is released. Accordingly, the continuous paper P is prevented from being excessively pulled out from the paper feed roll 11. As a result, the waste of the continuous paper P can be reduced.

(Rewinding Device) (Configuration)

FIG. 3 is a diagram schematically illustrating a more specific functional configuration example of the rewinding device 30. The rewinding device 30 includes, in addition to the configurations illustrated in FIG. 2, a brake unit 39, a RW motor 37 (reaction wheel motor, second motor), and a RW motor controller 38. Moreover, FIG. 3 illustrates a more specific configuration example of the moving roller holder 35.

As illustrated in FIG. 3, the continuous paper P sent in from the send-in port 31 is guided to the rewinding roll 36 while being brought into contact with a lower surface of the upstream guide roller 32, an upper surface of the downstream guide roller 33, and a lower surface of the moving roller 34 in this order.

The moving roller 34 is located below the downstream guide roller 33 and is rotatably supported on carriages 34 a configured to move on guide shafts G. The guide shafts G extend in a direction tilted at a predetermined angle with respect the direction of gravity. Tilting the extending direction of the guide shafts G with respect to the direction of gravity can reduce moving distance of the moving roller 34 in the direction of gravity and reduce the size of the rewinding device 30 in the up-down direction.

The length of the guide shafts G in this case is longer than the length of the moving range of the moving roller 34 in the conveyance of the continuous paper P. The moving range of the moving roller 34 is a range in which the moving roller 34 moves in the up-down direction when the RW motor controller 38 controls the rotation speed of the RW motor 37.

Note that the guide shafts G may extend in the direction of gravity. In this case, the guide rollers 32, 33 are arranged in the left-right direction at the same height. Moreover, the guide shafts G are provided between the guide rollers 32, 33 arranged at the same height.

The moving roller holder 35 is provided to extend on the right side of and along the guide shafts G. The moving roller holder 35 includes a holding stage drive motor 35 a, a drive pulley 35 b, a tail pulley 35 c, a belt 35 d, and the holding stage 35 e.

The holding stage 35 e is fixed to one portion of the belt 35 d and can be moved along the guide shafts G by movement of the belt 35 d. FIG. 3 illustrates an example in which the holding stage 35 e is arranged at a lower limit position of the guide shafts G.

The brake unit 39 is arranged between the moving roller 34 and the rewinding roll 36. The brake unit 39 includes paired guide rollers 39 a, 39 b and a brake roller 39 c around which the continuous paper P between the guide rollers 39 a, 39 b are wound.

The rewinding roll 36 formed by being rewound on the paper pipe 36 a is driven by the RW motor 37 via a speed reducer 36 b. The RW motor 37 is controlled by the RW motor controller 38.

The RW motor controller 38 is implemented by, for example, a computer including a ROM, a RAM, a CPU, and the like. The RW motor controller 38 controls operations of the RW motor 37, the holding stage drive motor 35 a, and the like by receiving instructions from the controller 22.

(Functions)

The moving roller 34 is movable on the guide shafts G. Moreover, the moving roller 34 applies tension to the continuous paper P laid between the upper surface of the downstream guide roller 33 and the upper surface of the guide roller 39 a by its own weight.

When the peripheral speed of the rewinding roll 36 just after the winding of the continuous paper P is higher than the send-in speed of the continuous paper P from the send-in port 31, the moving roller 34 moves upward along the guide shafts G. Meanwhile, when the peripheral speed of the rewinding roll 36 just after the winding of the continuous paper P is lower than the send-in speed of the continuous paper P, the moving roller 34 moves downward along the guide shafts G.

Specifically, the moving roller 34 is arranged between the send-in port 31 for the continuous paper P and the rewinding roll 36, applies tension to the conveyed continuous paper P while absorbing the speed difference between the send-in speed of the continuous paper P and the peripheral speed of the rewinding roll 36 just after the winding of the continuous paper P, and is movable in the up-down direction.

The brake unit 39 applies brake to the continuous paper P to apply tension to the continuous paper P between the downstream guide roller 33 and the rewinding roll 36. For example, a powder brake configured to generate braking force with an electromagnetic clutch using magnetic iron powder may be used as the brake roller 39 c. Note that the brake unit 39 is provided to mainly further stabilize the conveyance of the continuous paper P and is not an essential configuration.

The RW motor controller 38 controls the peripheral speed of the rewinding roll 36 based on the position of the moving roller 34 on the guide shafts G. Specifically, the RW motor controller 38 controls the RW motor 37 such that the RW motor 37 increases the peripheral speed of the rewinding roll 36 when the position of the moving roller 34 in the up-down direction moves downward from the center. Moreover, the RW motor controller 38 controls the RW motor 37 such that the RW motor 37 decreases the peripheral speed of the rewinding roll 36 when the position of the moving roller 34 in the up-down direction moves upward from the center. Such control allows the moving roller 34 to be located within its moving range in the up-down direction and keep applying tension to the continuous paper P by its own weight.

Moreover, the RW motor controller 38 controls the number of revolutions of the RW motor 37 based on control signals from the controller 22 of the conveying device 20. Note that the controller 22 may be included in the rewinding device 30. In this case, the RW motor controller 38 also generates the conveyance stop instruction. Specifically, some of the functions included in the controller 22 are included in the RW motor controller 38.

The functions in the conveyance of the continuous paper P have been described above. Functions in the case of stopping the conveyance of the continuous paper P are described in the following section of “Controller.”

(Controller)

In the operation of stopping conveyance of the continuous paper P, the controller 22 moves the moving roller 34 to the upper limit position in the moving range of the moving roller 34 in the up-down direction.

The numbers of revolutions (rpm) of the main shaft motor 21 and the RW motor 37 are controlled such that the conveyance speed of the continuous paper P becomes equal to the peripheral speed of rewinding roll 36 at which the continuous paper P is rewound (see description in (Functions)). As a result of the control, the position of the moving roller 34 in the up-down direction in the conveyance of the continuous paper P is near the center of the moving range of the moving roller 34.

FIG. 4 is a flowchart illustrating processing steps of the controller 22. Operations of the controller 22 are described with reference to FIG. 4. An example in which the controller 22 is included in the conveying device 20 is described. The controller 22 is implemented by, for example, a computer (controller) including a ROM, a RAM, a CPU, and the like.

The controller 22 starts the operations upon receiving the conveyance stop instruction generated when the conveying device 20 completes the conveyance of the continuous paper P corresponding to a predetermined number of copies (YES in step S10). The conveyance stop instruction is generated by the controller 22 of the conveying device 20.

The controller 22 starting the operations performs control which varies depending on the diameter of the rewinding roll 36. The controller 22 obtains information on the diameter of the rewinding roll 36 from the rewinding device 30.

When the diameter of the rewinding roll 36 is equal to or smaller than a first threshold Th₁ (YES in step S11), the controller 22 executes stop processing in which braking of the main shaft motor 21 is started before braking of the RW motor 37 (step S20). In this case, the force of inertia of the rewinding roll 36 is small and, since the diameter of the rewinding roll 36 is small, the peripheral speed of the rewinding roll 36 is low.

When the diameter of the rewinding roll 36 is larger than the first threshold Th₁ and is equal to or smaller than a second threshold Th₂ (YES in step S12), the controller 22 executes stop processing in which the braking of the main shaft motor 21 and the RW motor 37 are simultaneously started (step S30). In this case, the force of inertia and the peripheral speed of the rewinding roll 36 are at intermediate levels.

When the diameter of the rewinding roll 36 is larger than the second threshold Th₂ (NO in step S12), the controller 22 executes stop processing in which the braking of the RW motor 37 is started before the braking of the main shaft motor 21 (step S40). In this case, the force of inertia of the rewinding roll 36 is great and, since the diameter of the rewinding roll 36 is large, the peripheral speed of the rewinding roll 36 is high.

As described above, the controller 22 executes control which varies depending on the diameter (force of inertia and peripheral speed) of the rewinding roll 36. Each type of control is described in further detail with reference to FIG. 5 and other drawings. FIG. 5 is a diagram schematically illustrating a configuration example of the moving roller 34 as viewed in the conveyance direction of the continuous paper P.

(Case where Diameter of Rewinding Roll 36 is Small)

FIG. 6 is a flowchart illustrating processing steps of the controller 22 in the case where the diameter of the rewinding roll 36 is small (diameter of rewinding roll 36≥first threshold Th₁).

In this case, the controller 22 starts the braking of the main shaft motor 21 first (step S21). The position of the moving roller 34 just before the start of the braking of the main shaft motor 21 is the position in the conveyance of the continuous paper P and is near the center of the moving range. In this case, the holding stage 35 e is at the lower limit position of the moving range (FIG. 5).

As illustrated in FIG. 5, the moving roller 34 is rotatably supported on two carriages 34 a via a rotating shaft 34 b. The two carriages 34 a are movable on guide shafts G_(F), G_(R), respectively. A linear sensor 40 configured to detect the position of the moving roller 34 is arranged along the guide shaft G_(F).

The linear sensor 40 detects the position of a front end of a pointer 34 c extending from the rotating shaft 34 b as the position of the moving roller 34 on the guide shafts G_(F), G_(R). For example, the configuration may be such that the pointer 34 c is magnetized and the linear sensor 40 in which multiple Hall elements (not illustrated) are linearly arranged detects the position of the moving roller 34 in the up-down direction. In this case, the position detection can be performed at an accuracy of, for example, 0.1 mm or higher.

When the moving range of the moving roller 34 is assume to be, for example, 100 cm and the resolution of the position detection in the up-down direction is assumed to be, for example, 0.1 mm, the moving range can be expressed by 10-bit digital values (0 to 1023). The upper limit position of the moving roller 34 is set to, for example, 10 among these digital values.

Just after the start of the braking of the main shaft motor 21 (step S21), the conveyance speed of the continuous paper P becomes lower than the peripheral speed of the rewinding roll and the continuous paper P thus pulls the moving roller 34 upward from the position near the center in the up-down direction. The braking of the main shaft motor 21 may be performed by applying a mechanical brake (not illustrated) provided in the conveying device 20 or by performing control of reducing the number of revolutions of the main shaft motor 21.

The controller 22 detects the upward movement of the moving roller 34 from a detection signal of the linear sensor 40 (YES in step S22). The upward movement of the moving roller 34 triggers the controller 22 to start the control of gradually reducing the numbers of revolutions of the main shaft motor 21 and the RW motor 37 (step S23).

The linear sensor 40 repeatedly detects the position of the moving roller 34 (step S24). The control of reducing the numbers of revolutions of the main shaft motor 21 and the RW motor 37 is repeated until the moving roller 34 moves to the upper limit position in its moving range (NO in step S24).

As described above, since the controller 22 stops the conveyance of the continuous paper P while monitoring the position of the moving roller 34 in the up-down direction, the moving roller 34 can be stably moved to the upper limit position without departing from its moving range. Since the moving roller 34 moves to the upper limit position in the control of gradually reducing the numbers of revolutions of the main shaft motor 21 and the RW motor 37, no tension in a left-right direction of the continuous paper P is generated. Accordingly, the continuous paper P is not wound back toward the conveying device 20 even when the diameter of the paper feed roll 11 is large.

Moreover, since the numbers of revolutions of the main shaft motor 21 and the RW motor 37 are reduced such that the moving roller 34 is located within its moving range, the length of the moving range of the moving roller 34 can be reduced. Thus, the size of the rewinding device 30 can be reduced.

When the moving roller 34 moves to the upper limit position in its moving range (YES in step S24), the rotation of the main shaft motor 21 and the RW motor 37 is stopped (step S25). Then, the controller 22 moves the holding stage 35 e by causing the holding stage drive motor 35 a to rotate until the holding stage 35 e comes into contact with the carriages 34 a holding the moving roller 34 in a rotatable manner (step S26).

Whether the holding stage 35 e is in contact with the carriages 34 a or not can be detected from the detection signal of the linear sensor 40.

The moving roller 34 falls by its own weight when the rotation of the main shaft motor 21 and the RW motor 37 is stopped. This motion can be detected from a change in the digital value outputted by the linear sensor 40. For example, the digital value changes from (10) to (15).

The holding stage 35 e lifts the moving roller 34 having fallen by its own weight up to the upper limit position. Specifically, the controller 22 controls the holding stage drive motor 35 a such that the digital value outputted by the linear sensor 40 becomes the value (10) corresponding to the upper limit position of the moving roller 34. As a result, the moving roller 34 can be held at the upper limit position in its moving range.

The holding stage 35 e is fixed at the position where the tension applied to the continuous paper P by the weight of the moving roller 34 is released, based on the detection signal of the linear sensor 40 used to detect the position of the moving roller 34 in the up-down direction. A sensor for position control of the holding stage 35 e can be thus used also as a sensor for position control of the moving roller 34 and the number of parts can be reduced.

Although the example in which the moving roller 34 is moved to the upper limit position in its moving range and then the holding stage 35 e is moved is described, the present invention is not limited to this example. The holding stage 35 e may be moved to follow the movement of the moving roller 34.

The moving roller holder 35 moves the holding stage 35 e such that the holding stage 35 e follows the position of the moving roller 34 in the up-down direction. The amount of the moving roller 34 falling by its own weight after the stop of the rotation of the main shaft motor 21 and the RW motor 37 can be thereby minimized. Specifically, since the movement of the moving roller 34 in the up-down direction after its movement to the upper limit position can be suppressed, the conveyance quality of the continuous paper P does not decrease.

Note that the holding stage 35 e may be held by another method. The holding stage 35 e may be locked with a lock pin so as not to fall by the weight of the moving roller 34. Alternatively, a brake may be provided to prevent movement of the belt 35 d configured to move the holding stage 35 e. The lock pin and the brake are a general lock pin and a general brake.

As described above, when the diameter of the rewinding roll 36 is small (diameter of rewinding roll 36≤first threshold Th₁), the braking of the main shaft motor 21 is started before the braking of the RW motor 37 and the moving roller 34 is fixed to the upper limit position in its moving range. In this case, since the peripheral speed of the rewinding roll 36 is low, an upward change in the position of the moving roller 34 is gradual. Accordingly, the moving roller 34 can be moved to the upper limit position without departing from the moving range of the moving roller 34.

As a result, the length of the continuous paper P from the send-in port 31 to the rewinding roll 36 can be minimized. As a result, the waste of the continuous paper P can be reduced.

Modified Example

As described above, the moving roller 34 does not have to be held from below by the holding stage 35 e. In this section, a mechanism of pulling up the moving roller 34 to prevent it from falling is briefly described. When the moving roller is pulled up from above, the two carriages 34 a are suspended from above by wires (not illustrated), respectively. The length of each wire is controlled based on the detection signal of the linear sensor 40.

Then, when the controller 22 detects that the moving roller 34 has moved to the upper limit in its moving range by using the linear sensor 40, leading out of the wires is locked. Locking of the leading out of the wires may be performed by stopping rotation of a motor (not illustrated) configured to wind the wires or by using a mechanical brake. A mechanism for locking the leading out of the wires can be easily implemented.

(Case where Diameter of Rewinding Roll 36 is at Intermediate Level)

FIG. 7 is a flowchart illustrating processing steps of the controller 22 in the case where the diameter of the rewinding roll 36 is at the intermediate level (first threshold Th₁≥diameter of rewinding roll 36≥second threshold Th₂).

When the diameter of the rewinding roll 36 is at the intermediate level, the controller 22 starts the braking of the main shaft motor 21 and the RW motor 37 simultaneously (step S31). In this case, since there no large speed difference between the conveyance speed of the continuous paper P and the peripheral speed of the rewinding roll 36, the change of the moving roller 34 just after the start of the braking is gradual.

After the braking of the main shaft motor 21 and the RW motor 37 is started, the controller 22 performs speed control of reducing the numbers of revolutions of the main shaft motor 21 and the RW motor 37 such that the moving roller 34 moves to the upper limit position in its moving range (step S32). The speed control of the main shaft motor 21 and the RW motor 37 is repeated until the moving roller 34 moves to the upper limit position (NO in step S33).

Operations of step S32 and beyond are the same as those in the aforementioned case where the diameter of the rewinding roll 36 is small. As a result, it is possible to move the moving roller 34 to the upper limit position without departing from the moving range of the moving roller 34 and reduce the waste of the continuous paper P.

(Case where Diameter of Rewinding Roll 36 is Large)

FIG. 8 is a flowchart illustrating processing steps of the controller 22 in the case where the diameter of the rewinding roll 36 is large (diameter of rewinding roll 36≥second threshold Th₂).

When the diameter of the rewinding roll 36 is large, the controller 22 starts the braking of the RW motor 37 before the braking of the main shaft motor 21 (step S41). In this case, the force of inertia of the rewinding roll 36 is great and the peripheral speed of the rewinding roll 36 is high.

Accordingly, a decrease in the peripheral speed of the rewinding roll 36 is gradual and high peripheral speed is maintained. Thus, the web is rewound on the rewinding roll 36 and the moving roller 34 moves upward.

After the controller 22 detects the upward movement of the moving roller 34 (YES in step S42), the controller 22 starts the braking of the main shaft motor 21 (step S43). Operations hereafter are the same as those described above.

Starting the braking of the RW motor 37 before the braking of the main shaft motor 21 as described above allows the moving roller 34 to move to the upper limit position without departing from the moving range of the moving roller 34. As a result, the waste of the continuous paper P can be reduced.

Meanwhile, when the braking of the main shaft motor 21 is started first, the difference between the conveyance speed of the web and the peripheral speed of the rewinding roll 36 becomes excessively large. As a result, the moving roller 34 instantly moves (collides) to the upper limit position and there is a risk of breaking the rewinding device 30.

In the embodiment, it is possible to avoid rapid movement (collision) of the moving roller 34 and stably move the position of the moving roller 34 to the upper limit position. Accordingly, it is possible to reduce the waste of the continuous paper P and to also avoid breaking of the rewinding device 30. Moreover, since the moving range of the moving roller 34 can be reduced, the size of the rewinding device 30 can be reduced.

Table 1 is a table summarizing the aforementioned three cases.

TABLE 1 Diameter of rewinding roll Start of braking of main shaft motor Diameter of rewinding roll ≤ Th₁ Before RW motor Th₁ ≤ diameter of rewinding roll ≤ Th₂ Simultaneously with RW motor Th₂ ≤ diameter of rewinding roll After RW motor

As depicted in Table 1, when the diameter of the rewinding roll 36 of the rewinding device 30 is equal to or smaller than the first threshold Th₁, the controller 22 starts the braking of the main shaft motor 21 conveying the web in the conveying device 20 before the braking of the RW motor rotating the rewinding roll. When the diameter of the rewinding roll 36 of the rewinding device 30 is larger than the first threshold Th₁ and is equal to or smaller than the second threshold Th₂, the controller 22 starts the braking of the main shaft motor 21 and the RW motor 37 simultaneously. When the diameter of the rewinding roll 36 of the rewinding device 30 is larger than the second threshold Th₂, the controller 22 starts the braking of the RW motor 37 before the braking of the main shaft motor 21. This allows the moving roller 34 to stably move to the upper limit position without departing from its moving range and can reduce the waste of the continuous paper P.

(Error Processing)

FIG. 9 is a flowchart illustrating processing steps in error processing of the web conveying system 100 according to the embodiment. As described above, the conveying device 20 and the rewinding device 30 may be configured to be integrated. The error processing of the web conveying system 100 illustrated in FIG. 2 is described with reference to FIG. 9.

Errors of the web conveying system 100 include roughly three types of errors which are a drive-related error, a conveyance-related error, and a printing-related error. Although errors such as an operation-related error caused by bugs in firmware or the like may occur, description of such errors is omitted.

The drive-related error is an error caused by failure of the main shaft motor 21 and the RW motor 37. For example, the drive-related error is an error in which the conveyance of the continuous paper P becomes impossible due to heating, overcurrent, rotation failure, and the like in the motors.

The conveyance-related error is an error which occurs based on the cases such as meandering of the continuous paper P, tearing of the continuous paper P. and the diameter of the rewinding roll 36 reaching its limit.

The printing-related error is an error relating printing quality such as ink clogging and ink shortage in the inkjet head.

The web conveying system 100 executes stop processing which varies depending on the type of error. The controller 22 of the conveying device 20 and the RW motor controller 38 of the rewinding device 30 mainly perform the control of the stop processing in occurrence of an error.

When some sort of error occurs, the controllers start the error processing (YES in step S50). Error information indicating occurrence of the error is shared by the conveying device 20 and the rewinding device 30.

When the error is the drive-related error (YES in step S51), both controllers immediately stops the rotation of the main shaft motor 21 and the RW motor 37. In the drive-related error, emergency stop of both motors is performed.

When the error is the conveyance-related error (YES in step S52), both controllers execute stop processing in the conveyance-related error (step S70). This processing is described later.

When the error is the printing-related error (YES in step S53), both controllers execute the normal stop processing described in FIG. 4. In this case, the moving roller 34 can be stably moved to the upper limit position without departing from its moving range. As a result, the waste of the continuous paper P can be reduced.

FIG. 10 is a flowchart illustrating schematic processing steps of the stop processing in the conveyance-related error. In this case, both controllers execute processing corresponding to the diameter of the rewinding roll 36.

When the diameter of the rewinding roll 36 is larger than the second threshold Th₂ (YES in step S71), both controllers execute the stop processing in which the braking of the RW motor 37 is started before the braking of the main shaft motor 21 (step S72). When the diameter of the rewinding roll 36 is equal to or smaller than the second threshold Th₂ (NO in step S71), both controllers execute the stop processing in which the braking of the main shaft motor 21 is started before the braking of the RW motor 37 (step S73). The stop processing in which the braking of the main shaft motor 21 is started before the braking of the RW motor 37 is the same as the processing in steps S21 to S26 (FIG. 6).

FIG. 11 is a flowchart more specifically describing the processing of step S72. When the error is the conveyance-related error and the diameter of the rewinding roll 36 is larger than the second threshold Th₂, both controllers start the braking of the RW motor 37 (step S720). Next, both controllers start the braking of the main shaft motor 21 (step S721).

The order of the braking is the same as that in the case where the diameter of the rewinding roll 36 is large (diameter of rewinding roll 36≥second threshold Th₂) as described with reference to FIG. 8. However, in the normal condition (case of no error), after the start of the braking of the RW motor 37, the upward movement of the moving roller 34 is detected and then the braking of the main shaft motor 21 is started (step S43).

Meanwhile, in the case of the conveyance-related error, after the start of the braking of the RW motor 37, the braking of the main shaft motor 21 is immediately started. The braking is different because the conveyance of the continuous paper P is desired to be stopped more quickly than in the normal condition. In other words, the time difference between the start of the braking of the RW motor 37 and the start of the braking of the main shaft motor 21 in the conveyance-related error is smaller than that in the normal condition. This allows the conveyance of the continuous paper P in the conveyance-related error to be stopped more quickly than in the normal condition and also allows the moving roller 34 to move to the upper limit position without departing the moving range of the moving roller 34.

The error processing described with reference to FIGS. 9 and 11 can be performed similarly in the web conveying device 23 configured by integrating the conveying device 20 and the rewinding device 30.

As described above, the web conveying device 23 can reduce the waste of the continuous paper P. Moreover, since the stop processing is executed such that the moving roller 34 does not depart from its moving range, it is possible to reduce the moving range and reduce the size of the rewinding device 30.

Although description is given of the example in which the moving direction of the moving roller 34 in the aforementioned embodiment has a tilt angle with respect to the direction of gravity, the present invention is not limited to this example. The moving direction of the moving roller 34 may be the direction of gravity. Moreover, although the continuous paper P is described as an example of the web, the web may a film or the like.

OTHERS

The invention is not limited to the aforementioned embodiment as it is and may be implemented with the components therein modified within the scope not departing from the spirit of the invention in a stage of carrying out the invention. Moreover, various inventions can be formed by appropriately combining the multiple components disclosed in the aforementioned embodiment. For example, some of components among all components described in the embodiment may be omitted.

Moreover, for example, processing and function described above may be implemented by one or more processing circuits. The processing circuits include programmed processors, electric circuits, and the like and also include devices such as an application-specific integrated circuit (ASIC), circuit components arranged to execute the described functions, and the like.

The present application is based on and claims the benefit of priority from Japanese Patent Application No. 2019-025462, filed on Feb. 15, 2019, the entire contents of which are incorporated herein by reference.

REFERENCE SIGNS LIST

-   10 paper feeding device (web feeding device) -   11 paper feed roll -   20 conveying device (printing device) -   21 main shaft motor -   22 controller -   23 web conveying device -   30 rewinding device -   31 send-in port -   32 upstream guide roller -   33 downstream guide roller -   34 moving roller -   34 a carriage -   35 moving roller holder -   35 a holding stage drive motor -   35 b drive pulley -   35 c tail pulley -   35 d belt -   35 e holding stage -   36 rewinding roll -   36 a paper pipe -   36 b speed reducer -   37 RW motor -   38 RW motor controller -   39 brake unit -   39 a guide roller -   39 b guide roller -   39 c brake roller 

What is claimed is:
 1. A web conveying device configured to convey a web and rewind the web into a roll, comprising: a moving roller arranged between a send-in port for the web and a rewinding roll which is the web rolled, the moving roller configured to be movable in an up-down direction to apply tension to the web or release the tension; and a controller configured to perform control of moving the moving roller to an upper limit position in the up-down direction in an operation of stopping conveyance of the web.
 2. The web conveying device according to claim 1, wherein the controller starts braking of a first motor configured to convey the web before braking of a second motor configured to rotate the rewinding roll when a diameter of the rewinding roll is equal to or smaller than a first threshold, starts the braking of the first motor and the second motor simultaneously when the diameter of the rewinding roll is larger than the first threshold and is equal to or smaller than a second threshold, and starts the braking of the second motor before the braking of the first motor when the diameter of the rewinding roll is larger than the second threshold.
 3. The web conveying device according to claim 1, further comprising a moving roller holder configured to release the tension by using a holding stage configured to hold the moving roller and prevent the moving roller from falling in the operation of stopping conveyance of the web, wherein the moving roller holder moves the holding stage such that the holding stage follows the position of the moving roller in the up-down direction.
 4. The web conveying device according to claim 2, further comprising a moving roller holder configured to release the tension by using a holding stage configured to hold the moving roller and prevent the moving roller from falling in the operation of stopping conveyance of the web, where the moving roller holder moves the holding stage such that the holding stage follows the position of the moving roller in the up-down direction. 